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| author | Johannes Weiner <hannes@cmpxchg.org> | 2012-07-31 16:45:50 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-07-31 18:42:49 -0700 |
| commit | bdf4f4d2161a795b9323855a81a047bd68f16202 (patch) | |
| tree | 3aa457660c69f2945cb9ab477079e7441f220b27 /mm | |
| parent | 90deb78839faedd194b65d419dbd9cba981e1922 (diff) | |
| download | linux-bdf4f4d2161a795b9323855a81a047bd68f16202.tar.gz linux-bdf4f4d2161a795b9323855a81a047bd68f16202.tar.bz2 linux-bdf4f4d2161a795b9323855a81a047bd68f16202.zip | |
mm: memcg: only check anon swapin page charges for swap cache
shmem knows for sure that the page is in swap cache when attempting to
charge a page, because the cache charge entry function has a check for it.
Only anon pages may be removed from swap cache already when trying to
charge their swapin.
Adjust the comment, though: '4969c11 mm: fix swapin race condition' added
a stable PageSwapCache check under the page lock in the do_swap_page()
before calling the memory controller, so it's unuse_pte()'s pte_same()
that may fail.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Wanpeng Li <liwp.linux@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memcontrol.c | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1a2020d72ca0..b06833f2b89e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2818,14 +2818,6 @@ static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm, return 0; if (!do_swap_account) goto charge_cur_mm; - /* - * A racing thread's fault, or swapoff, may have already updated - * the pte, and even removed page from swap cache: in those cases - * do_swap_page()'s pte_same() test will fail; but there's also a - * KSM case which does need to charge the page. - */ - if (!PageSwapCache(page)) - goto charge_cur_mm; memcg = try_get_mem_cgroup_from_page(page); if (!memcg) goto charge_cur_mm; @@ -2848,6 +2840,20 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page, *memcgp = NULL; if (mem_cgroup_disabled()) return 0; + /* + * A racing thread's fault, or swapoff, may have already + * updated the pte, and even removed page from swap cache: in + * those cases unuse_pte()'s pte_same() test will fail; but + * there's also a KSM case which does need to charge the page. + */ + if (!PageSwapCache(page)) { + int ret; + + ret = __mem_cgroup_try_charge(mm, gfp_mask, 1, memcgp, true); + if (ret == -EINTR) + ret = 0; + return ret; + } return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp); } |